Abstract

This work deals with the detection of water aquifers and the delineation of subsurface structures predominant in the basement rocks, and their relationship with these aquifers, at west Lake Nasser, southwestern desert, Egypt. An integrated study using geoelectric, geomagnetic, and well logging methods was conducted. Geoelectric surveys were initially performed to obtain vertical electrical sounding (VES) profiles to identify the subsurface geoelectric layers predominant in the area. This was followed by land magnetic surveys using a proton precession magnetometer in a mesh-like network covering the area of investigation. These surveys allowed us to determine the depth to basement rock, and establish the subsurface structures and their relation with the detected aquifers. To confirm the results, more than 20 boreholes were drilled and logged within the study area to determine the distribution of the subsurface water reservoirs and geological sequences in the area.

The results indicate that the depth to the main water aquifer, represented by saturated Nubian sandstone, ranges from 80 to 100 m. The thickness of this reservoir varies from 100 to 150 m. The Nubian sandstone formation consists of three members (layers) that unconformably overlie the basement rocks. The depth to the basement rocks ranges from 100 to 250 m. The structure trend analyses indicate that the dominant tectonic trends are NW, NE, and Aqaba trends. These structures play an important role in the water supply from Lake Nasser and recharging the main water aquifer.